Denitrification and nitrate reduction to NH/sub 4//sup +/-N and organic N were investigated in the laboratory using surface samples of Histosols and Ultisols. A wide range of pH (3.4 to 7.3) was obtained by liming acidic virgin soils and by selecting a range of field-limed soils. When incubated under waterlogged conditions in the presence of glucose for 2 d at 25/sup 0/C, there was a very low loss of NO/sub 3//sup -/-N below a pH of 4.0 and an increase in NO/sub 3//sup -/-N loss with pH up to a pH of 6.0. After 12 d of incubation, NO/sub 3//supmore » -/-N loss (105-115 mg L/sup -1/) was complete from soils at all pH values. Laboratory and field-limed soils behaved as expected from their pHs. For soils incubated for 2 d without glucose, there was a moderate effect of soil pH upon NO/sub 3//sup -/-N loss. For incubations longer than 2 d soluble C appeared to be more important than pH in controlling loss of NO/sub 3//sup -/-N. Soils with pH <4.0 showed unexpectedly high NO/sub 3//sup -/-N loss when incubated for periods >12 d without glucose. Experiments with /sup 15/NO/sub 3//sup -/-N showed that 16 to 20% of the NO/sub 3//sup -/-N loss in soils with pH <4.0 was due to reduction to NH/sub 4//sup +/-N and orgainc N but only 1 to 2% for soils with pH >4.0. Evidence indicates that the reduction was dissimilatory and unrelated to levels of soluble C. Denitrification was substantial in the soils with pH <4.0 and of a similar level to that for moderately acidic soils (pH 4.4-5.4). In the neutral soils (pH 6.9-7.3) denitrification was much higher but much of the increase appeared due to the higher level of soluble C.« less

Most of the coastal wetlands of the South Atlantic region of the United States are expected to diminish in size in response to increasing human population growth and accelerating rates of rising sea level. after examination of the distribution of wetlands, elevation contours, estimates of surface slope, soil types, and peat deposits on the peninsula, current models were considered unsuited for wetlands of the Albemarle-Pamlico peninsula of North Carolina. Some unusual features of this peninsula are low elevation (56% of total area <1.5 m), extensive coverage by wetlands (53%) and hydric soils (90%), negligible slopes of the land surface, virtualmore » absence of tides, and lack of abundant sources of sediment. In the process of reconstructing how past rises in sea level most likely led to present conditions, it became apparent that vertical accretion of peat in situ is largely responsible for landscape features in areas where elevations are lowest. Were it not for these deposits, the land surface area of the peninsula would be decreasing relative to sea level. This situation contrasts sharply with areas in the eastern United States fringed by tidal marshes, which are undergoing overland migration at a rate dictated by landward slope and the rate of rising sea level. If the rate of sea level rise accelerates, it is doubtful if vertical accretion rates of peat can prevent submergence of extensive areas of wetlands in the Albemarle-Pamlico peninsula. Land use and drainage in the lowest elevations of the peninsula are currently being affected by sea level. Future land management of the peninsula will be constrained by potential landscape changes as a result of rising sea level. 28 refs., 6 figs., 5 tabs.« less

Glitzenstein, J.S., Donna R. Streng, D.D. Wade, and J. Brubaker. 2001. Starting new populations of longleaf pine ground-layer plants in the Outer Coastal Plain of South Carolina, USA. Natural Areas J. 21:89-110. Abstract: Southeastern United States habitats dominated by longleaf pine (Pinus palustris Miller) and associated plant species have declined dangerously. Conservation of rare and common plants of longleaf pine habitats may be aided by starting new populations in the field. We review methods for initiating plant populations and integrate information from our studies of rare and common longleaf pine ground-layer plants of the outer South Carolina Coastal Plain. Inmore » our experience it is possible to start new populations of most longleaf pine ground-layer plants, including rare species if (1) seeds are collected from frequently burned sites with reasonably large populations of desired species; (2) appropriate media are used for seedling propagation; (3) outplanting of nursery grown seedlings or direct seeding is done during periods of sufficient soil moisture; and (4) introduction sites properly match habitat requirements (inferred from indicator plants) of desired species, and the sites can be managed with frequent prescribed fire.« less

Abstract: Southeastern United States habitats dominated by longleaf pine (Pinus palustris Miller) and associated plant species have declined dangerously. Conservation of rare and common plants of longleaf pine habitats may be aided by starting new populations in the field. We review methods for initiating plant populations and integrate information from our studies of rare and common longleaf pine ground-layer plants of the outer South Carolina Coastal Plain. In our experience it is possible to start new populations of most longleaf pine ground-layer plants, including rare species if (1) seeds are collected from frequently burned sites with reasonably large populations ofmore » desired species; (2) appropriate media are used for seedling propagation; (3) outplanting of nursery grown seedlings or direct seeding is done during periods of sufficient soil moisture; and (4) introduction sites properly match habitat requirements (inferred from indicator plants) of desired species, and the sites can be managed with frequent prescribed fire.« less

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